An FSC color liquid crystal display device incorporates three light sources of red, green, and blue (hereinafter abbreviated “R,” “B,” and “B,” respectively) which differ in wavelength, and forces the three light sources to emit lights of frequencies of 60 Hz or higher sequentially. Further, an FSC color liquid crystal display device applies a drive voltage to a liquid crystal in synchronization with the timing of light emission of each of its light sources thereby producing a color display (e.g. Patent Document 1).
To prevent color break-up due to R, G and B colors which arises in an FSC color display device, there has been known a method of producing a color display by making four light sources of R, G and B colors, and white color (hereinafter abbreviated “W color”) emit lights sequentially (e.g. Patent Document 2). Color break-up refers to a phenomenon in that e.g. a point on an edge of a W color display shifts, leading to interference with R, G, and B colors in that portion, and thus the portion seems to have a color that is different from a desired color. This is attributable to the movement of the human eye, such as tracking in which the human eye tracks a moving object on a screen. In other words, the color break-up refers to a phenomenon in that R, G and B color images are slightly shifted by time differences when a scene such as a white object moving on a screen is displayed with R, G, and B colors, whereby an edge of the white object ends up being a color different from a desired color.
As for an FSC color display device, a method of producing a color display by forcing four light sources of R, G, B and W to light independently has been known (e.g. Patent Document 3). FIG. 11 is a drawing showing an example of a group of timing charts in association with such method, in which a lighting control signal 1101 coming from an R-LED, a lighting control signal 1102 from a G-LED, a lighting control signal 1103 from a B-LED, and a lighting control signal 1104 from a W-LED are shown. It is noted for the control signals that “H” level represents that each color LED is in its lighting mode, and “L” level represents that the color LED stays in its unlit mode. As shown in FIG. 11, the R-LED is turned on in the first subfield (period T1) of a field (period Tf), the G-LED is turned on in the second subfield (period T2), the B-LED is turned on in the third subfield (period T3), and the W-LED is turned on in the fourth subfield (period T4).    Patent Document 1: Japanese Unexamined Patent Publication No. H05-19257    Patent Document 2: Japanese Unexamined Patent Publication No. 2002-72980 (FIG. 8)    Patent Document 3: Japanese Unexamined Patent Publication No. 2004-4626 (FIG. 1)